Profit maximization in a monopolistic business environment is achieved when the Marginal revenue is equal to the marginal cost (MR = MC). The average total cost should come below the market price for the firm to earn an economic profit.
Using the Diagram, the marginal Revenue Curve intersect with the Marginal Cost function Curve at a maximizing Quantity of 400 Units which gives an optimal demand price of 100. This is the price and quantity the firm should produce to maximize its profits. If the firm decided to produce less units say (240 Units) where the MRMC the company would be making a profit per unit but this will reduce the demand for the product.
Therefore, the optimal demand price and Quantity for this type of market is at 400 Units and a demand price of 100.